Differential modulation of motor evoked potential and silent period by activation of intracortical inhibitory circuits

2001 ◽  
Vol 112 (10) ◽  
pp. 1822-1827 ◽  
Author(s):  
Carlo Trompetto ◽  
Alessandro Buccolieri ◽  
Lucio Marinelli ◽  
Giovanni Abbruzzese
Keyword(s):  
Evoked Potential ◽  
Motor Evoked Potential ◽  
Silent Period ◽  
Differential Modulation ◽  
Inhibitory Circuits

A new concept in the electrophysiological evaluation of syringomyelia

2008 ◽  
Vol 8 (6) ◽  
pp. 517-523 ◽  
Author(s):  
Florian Roser ◽  
Florian H. Ebner ◽  
Marina Liebsch ◽  
Klaus Dietz ◽  
Marcos Tatagiba
Keyword(s):  
Evoked Potential ◽  
Clinical Symptoms ◽  
Early Stage ◽  
Motor Evoked Potential ◽  
Silent Period ◽  
Preoperative Assessment ◽  
Central Canal ◽  
Spinothalamic Tract ◽  
Specific Symptom ◽  
Electrophysiological Measurements

Object The current neurophysiological assessment of syringomyelia is inadequate. Early-stage syringomyelia is anatomically predisposed to affect decussating spinothalamic fibers that convey pain and sensation primarily. Silent periods have been proven to be a sensitive tool for detecting alterations in this pathway. Methods Thirty-seven patients with syringomyelia were included in this prospective study. Routine electrophysiological measurements were applied including somatosensory evoked potential (SSEP) and motor evoked potential (MEP) recordings for all extremities. The silent periods were recorded from the pollicis brevis muscle, and electrical stimuli were applied to the ipsilateral digiti II. To establish baseline values, the authors had 28 healthy controls undergo monitoring. Sensitivity and specificity values were statistically evaluated according to the main clinical symptoms (paresis, dissociative syndrome, and pain). Results All control individuals had normal silent periods in voluntarily activated muscle. In syringomyelia patients, the affected limb showed pathological silent periods with all symptoms (sensitivity 30–50%). Pain was the most specific symptom (90%), despite SSEP and MEP values that were within the normal range. Conclusions Silent period testing is a sensitive neurophysiological technique and an invaluable tool for preoperative assessment of syringomyelia. Silent periods are associated with early dysfunction of thin myelinated spinothalamic tract fibers, even when routine electrophysiological measurements still reveal normal values. Conduction abnormalities that selectively abolish the silent periods can distinguish between hydromyelia (a physiologically dilated central canal) and space-occupying syringomyelia.

Stereotactic pallidotomy lengthens the transcranial magnetic cortical stimulation silent period in Parkinson's disease

Neurology ◽  
1997 ◽  
Vol 49 (5) ◽  
pp. 1278-1283 ◽  
Author(s):  
M. S. Young ◽  
W. J. Triggs ◽  
D. Bowers ◽  
M. Greer ◽  
W. A. Friedman
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Globus Pallidus ◽  
Motor Evoked Potential ◽  
Silent Period ◽  
Cortical Stimulation ◽  
Abductor Pollicis Brevis ◽  
Inhibitory Circuits ◽  
Before And After ◽  
Transcranial Magnetic Cortical Stimulation

We compared the duration of the EMG cortical stimulation silent period(CSSP) elicited in abductor pollicis brevis using transcranial magnetic stimulation (TMS) before and after stereotactic unilateral globus pallidus internus pallidotomy (PAL) in 12 patients with Parkinson's disease. We used TMS stimulus intensities of 200, 150, 120, and 100% of motor evoked potential(MEP) threshold before and after (86 ± 25 days) PAL. PAL increased CSSP duration at stimulus intensities of 200% of MEP threshold in the hand contralateral to the stereotactic lesion. In a subset of five patients able to remain at rest during pre-PAL testing sessions, PAL decreased the resting MEP/M-wave area ratio in the hand contralateral to the lesion at a stimulus intensity of 120% of MEP threshold. PAL did not significantly modify the effects of TMS in the hand ipsilateral to the globus pallidus lesion. The results suggest that PAL improves the function of cortical motor inhibitory circuits in Parkinson's disease.

scholarly journals Mechanisms and Dynamics of Cortical Motor Inhibition in the Stop-signal Paradigm: A TMS Study

2010 ◽  
Vol 22 (2) ◽  
pp. 225-239 ◽  
Author(s):  
Wery P. M. van den Wildenberg ◽  
Borís Burle ◽  
Franck Vidal ◽  
Maurits W. van der Molen ◽  
K. Richard Ridderinkhof ◽  
...  
Keyword(s):  
Time Course ◽  
Primary Motor Cortex ◽  
Motor Evoked Potential ◽  
Silent Period ◽  
Single Pulse ◽  
Stop Signal ◽  
Neural Basis ◽  
Manual Response ◽  
Inhibitory Circuits ◽  
Voluntary Behavior

The ability to stop ongoing motor responses in a split-second is a vital element of human cognitive control and flexibility that relies in large part on prefrontal cortex. We used the stop-signal paradigm to elucidate the engagement of primary motor cortex (M1) in inhibiting an ongoing voluntary motor response. The stop-signal paradigm taps the ability to flexibly countermand ongoing voluntary behavior upon presentation of a stop signal. We applied single-pulse TMS to M1 at several intervals following the stop signal to track the time course of excitability of the motor system related to generating and stopping a manual response. Electromyography recorded from the flexor pollicis brevis allowed quantification of the excitability of the corticospinal tract and the involvement of intracortical GABABergic circuits within M1, indexed respectively by the amplitude of the motor-evoked potential and the duration of the late part of the cortical silent period (SP). The results extend our knowledge of the neural basis of inhibitory control in three ways. First, the results revealed a dynamic interplay between response activation and stopping processes at M1 level during stop-signal inhibition of an ongoing response. Second, increased excitability of inhibitory interneurons that drives SP prolongation was evident as early as 134 msec following the instruction to stop. Third, this pattern was followed by a stop-related reduction of corticospinal excitability implemented around 180 after the stop signal. These findings point to the recruitment of GABABergic intracortical inhibitory circuits within M1 in stop-signal inhibition and support the notion of stopping as an active act of control.

Supraspinal fatigue during intermittent maximal voluntary contractions of the human elbow flexors

2000 ◽  
Vol 89 (1) ◽  
pp. 305-313 ◽  
Author(s):  
Janet L. Taylor ◽  
Gabrielle M. Allen ◽  
Jane E. Butler ◽  
S. C. Gandevia
Keyword(s):  
Evoked Potential ◽  
Intermittent Exercise ◽  
Human Subjects ◽  
Motor Evoked Potential ◽  
Silent Period ◽  
Central Fatigue ◽  
Duty Cycles ◽  
Flexor Muscles ◽  
Elbow Flexor Muscles ◽  
Voluntary Contractions

Responses to transcranial magnetic stimulation in human subjects ( n = 9) were studied during series of intermittent isometric maximal voluntary contractions (MVCs) of the elbow. Stimuli were given during MVCs in four fatigue protocols with different duty cycles. As maximal voluntary torque fell during each protocol, the torque increment evoked by cortical stimulation increased from ∼1.5 to 7% of ongoing torque. Thus “supraspinal” fatigue developed in each protocol. The motor evoked potential (MEP) and silent period in the elbow flexor muscles also changed. The silent period lengthened by 20–75 ms (lowest to highest duty cycle protocol) and recovered significantly with a 5-s rest. The MEP increased in area by >50% in all protocols and recovered significantly with 10 s, but not 5 s, of rest. These changes are similar to those during sustained MVC. The central fatigue demonstrated by the torque increments evoked by the stimuli did not parallel the changes in the electromyogram responses. This suggests that part of the fatigue developed during intermittent exercise is “upstream” of the motor cortex.

The effect of acetaminophen ingestion on cortico-spinal excitability

2013 ◽  
Vol 91 (2) ◽  
pp. 187-189 ◽  
Author(s):  
Alexis R. Mauger ◽  
James G. Hopker
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Evoked Potential ◽  
Motor Evoked Potential ◽  
Silent Period ◽  
Sodium Currents ◽  
Cortical Silent Period ◽  
Voltage Gated ◽  
Spinal Excitability

Acetaminophen (ACT) facilitates the inhibition of voltage-gated calcium and sodium currents, which may effect cortico-spinal excitability. Twelve subjects ingested acetaminophen or a placebo and underwent transcranial magnetic stimulation to assess the motor evoked potential (MEP), and cortical silent period (CSP). ACT significantly increased MEP response (P > 0.05) but had no effect on CSP (P > 0.05). This indicates that ACT increases MEP and should be controlled for in studies where these measures are of interest.

scholarly journals Perimenopausal women show modulation of excitatory and inhibitory neuromuscular mechanisms

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Heidi Pesonen ◽  
Eija K. Laakkonen ◽  
Pekka Hautasaari ◽  
Pauliina Aukee ◽  
Vuokko Kovanen ◽  
...  
Keyword(s):  
Evoked Potential ◽  
Motor Evoked Potential ◽  
Silent Period ◽  
Neuromuscular Control ◽  
Lower Limbs ◽  
Cortical Inhibition ◽  
Muscle Quality ◽  
Twitch Force ◽  
Peripheral Muscle ◽  
Increased Risk

Abstract Background Menopausal transition exposes women to an early decline in muscle force and motor function. Changes in muscle quality and function, especially in lower limbs, are crucial, as they expose individuals to increased risk of falls. To elucidate some of the related neuromuscular mechanisms, we investigated cortical inhibition and peripheral muscle twitch force potentiation in women during the early and late stages of perimenopause. Methods Participants were 63 women aged 48–55 years categorized as early (EP, n = 25) or late (LP, n = 38) perimenopausal according to serum follicle-stimulating hormone (FSH) levels and menstrual diaries. EP women had an irregular menstrual cycle and FSH < 25 IU/L, while LP women had an irregular cycle and > 25 IU/L. We examined motor evoked potential (MEP) and silent period (SP) elicited by transcranial magnetic stimulation (TMS), in the tibialis anterior muscle at 20%, 40%, and 60% of maximal voluntary contraction (MVC) levels, and twitch force potentiation in plantar flexors. Results EP group showed a longer SP duration in 40% MVC condition and larger motor evoked potential amplitude in 20% MVC condition compared to the LP group. No group difference was detected in twitch force potentiation; however, it correlated negatively with FSH levels. Other factors, such as age, height, body mass index, or physical activity did not explain group differences. Conclusions Our preliminary results indicate subtle modulation in both TMS-induced inhibitory and excitatory mechanisms and twitch force potentiation in women already in the late perimenopausal stage. This suggests that the reduction of estrogens may have an accelerating role in the aging process of neuromuscular control.

scholarly journals Duration and reliability of the silent period in individuals with spinal cord injury

2020 ◽  
Author(s):  
Hannah Sfreddo ◽  
Jaclyn R. Wecht ◽  
Ola Alsalman ◽  
Yu-Kuang Wu ◽  
Noam Y. Harel
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Evoked Potential ◽  
Motor Evoked Potential ◽  
Silent Period ◽  
List Type ◽  
Abductor Pollicis Brevis ◽  
Resting Motor Threshold ◽  
Cord Injury ◽  
Period Duration

ObjectiveWe aim to better understand the silent period (SP), an inhibitory counterpart to the well-known motor evoked potential (MEP) elicited by transcranial magnetic stimulation (TMS), in individuals with spinal cord injury (SCI).MethodsElectromyographic responses were measured in the target abductor pollicis brevis at rest (TMS at 120% of resting motor threshold (RMT)) and during maximal effort (TMS at 110% of RMT). Participants with chronic cervical SCI (n=9) and able-bodied volunteers (n=12) underwent between 3-7 sessions of stimulation on separate days. The primary outcomes were the magnitude and reliability of SP duration, resting and active MEP amplitudes, and RMT.ResultsSCI participants showed significantly increased RMT, decreased MEP amplitudes, and non-significantly longer SP duration compared to AB participants. In contrast to high inter-participant variability, SP duration demonstrated reduced intra-participant variability within and across sessions compared with resting and active MEP amplitudes. SCI participants also demonstrated a higher prevalence of SP ‘interruptions’ compared to AB participants.ConclusionsSP reflects a balance between corticospinal excitatory and inhibitory processes. SP duration is more reliable within and across multiple sessions than MEP amplitude.SignificanceThe higher reliability of SP duration may make it a useful outcome measure for future trials of SCI interventions.HighlightsWe compared characteristics of the silent period between individuals with spinal cord injury and able-bodied volunteers.Silent period duration was insignificantly longer in spinal cord injury individuals.Silent period duration was found to be a more reliable within-subject metric than motor evoked potential amplitude.

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